For many years by now, projectors using a metal halide lamp and the like as the light source, whereby video images displayed on liquid crystal panels are enlarged and projected on a screen, have been available on the market.
With such projectors, the light emitted from the light source is gathered on liquid crystal panels by means of mirrors and the like and projected on a screen through a projection lens.
There are two kinds of liquid crystal display projectors, one being a 1-panel type that employs one liquid crystal display panel and the other being a 3-panel type wherein three liquid crystal display panels are used and color splitting and color combining are performed by means of dichloic mirrors and the like.
Each respective type of the above has a projection lens protruding from the projector's main body cabinet.
As shown in FIG. 6, a 1-panel type liquid crystal display projector has, in general, a projection lens 41, a field lens 42, a liquid crystal display panel 43 and polarizers 45 for light incident side and light radiant side.
There are two types in the projection lens 41, one having a fixed focus length and the other having a zooming function.
A 3-panel type liquid crystal display projector is basically of the same structure except for having half mirrors 44 that are additionally built in for color splitting and combining.
These types of liquid crystal display projectors were proposed in a Japanese patent application published for public examination, Showa 62(1987)-316710, for example.
Each respective liquid crystal display projector of 1-panel type and 3-panel type has generally a structure wherein a projection lens protrudes from the main body cabinet of the projector due to limitations in layout.
The structure wherein the projection lens protrudes has often caused a problem of damaging the protruding lens and the like when a liquid crystal display projector is carried. In addition, the protruding projection lens has imposed many restrictions on designing liquid crystal display projectors, thereby leading to a reduction in freedom of design. Furthermore, there is a drawback that dust easily settles on a protruding projection lens.